Software developed for calculation of optimum cutoff grades

Abstract:
      One of the most important aspects of mine design is to determine the optimum cut-off grades. Material grading above and below the cut-off is directed to different destinations. Optimizing the cutoff grades of ore has long been recognized as a means to maximize the net present value (NPV) of a mining project. Maximizing the NPV of a mining operation, subject to different constraints is a non-linear programming problem. This paper describes a program, which is developed by Matlab 6 software to find the optimum cutoff grades that will maximize the NPV. All data input to this program are in the form of two text files. One contains information on grade distribution of each pushback. The other contains information of price, mining, processing, and refining costs, recovery in each stage, discount rate, the required cutoffs accuracy, fixed costs and the throughput limits. These text files must be produced as M file at Matlab software. This program helps to calculate the optimum NPV over the life of the mine and the output obtained by this software gives the cutoff grades policy and the optimum production schedule.